ray-picking

问题 I’m trying to implement GPU picking with Points using code I modified from the latter half of this article https://threejsfundamentals.org/threejs/lessons/threejs-picking.html It’s been working fine for me on desktop, but I started testing different browsers and devices and it doesn’t work consistently. I made a Codepen to illustrate https://codepen.io/deklanw/pen/OJVVmEd?editors=1111 body { margin: 0; } #c { width: 100vw; height: 100vh; display: block; } <canvas id="c"></canvas> <script type

问题 I need some help on 3D picking. I am using the way it works here. In short, what I have is: normalizedPoint[0] = (x * 2 / screenW) -1; normalizedPoint[1] = 1 - (y * 2 / screenH); normalizedPoint[2] = ? normalizedPoint[3] = ? for 2 and 3, I have no idea what it should be (I put 1, -1 just like the reference, and it doesn't work) Then, for my root object (following just psuedo code): matrix = perspective_matrix x model_matrix inv_matrix = inverse(matrix) outpoint = inv_matrix x normalizedPoint

问题 I couldn't find the correct and understandable expression of picking in 3D with method of ray-tracing. Has anyone implemented this algorithm in any language? Share directly working code, because since pseudocodes can not be compiled, they are genereally written with lacking parts. 回答1: What you have is a position in 2D on the screen. The first thing to do is convert that point from pixels to normalized device coordinates — -1 to 1. Then you need to find the line in 3D space that the point

问题 So I have been looking through tutorials (And questions on this site) and have found nothing to solve my problem. Here is the current code I am trying to implement: private void pick() { float[] matModelView = new float[16], matProjView = new float[16]; int[] view = new int[16]; float mouseX = width / 2; float mouseY = height / 2; Vector3f start = new Vector3f(); Vector3f end = new Vector3f(); FloatBuffer modelBuffer = compileBuffer(matModelView); FloatBuffer projBuffer = compileBuffer

问题 I am working on a project which allows users to pick 3d objects in a scene and I was wondering what everyone thought would be the best way to approach this particular scenario. Basically we have a scene with at least 100 objects (they are low-poly but made from at least ~12-15 triangles) and up to about 1000-2000 objects. Not all the objects will be "pickable" at all times because some objects will occlude others so "pickable" objects probably land in the range between 800-1500 (depending on

问题 How to implement 3d raypicking in an 3d scene with models that contain high poly meshes? It takes too much time to iterate over all triangles to perform a triangle-line-intersection test. I know that there exist methods like octree etc. and it should be possible to use these for the models in the scene, but I do not know how I should use these concepts at mesh-level. But if you use an octree at mesh-level, how should one cover problems with polygons, that exceed the boundaries of the octree

问题 Ok so I was able to get the coordinates in 3d space for the touch now I need to test whether that ray intersected a triangle. What I am asking is for help to understand the Test Class. BTW this code came from http://android-raypick.blogspot.ca/2012/04/first-i-want-to-state-this-is-my-first.html. I know to pass in the ray and an empty float array into intersectRayAndTriangle() but the Test T is the V0[], V1[], and V2[] but where do I get those at? Are they the converted coordinates of my

问题 I try to use what many people seem to find a good way, I call gluUnproject 2 times with different z-values and then try to calculate the direction vector for the ray from these 2 vectors. I read this question and tried to use the structure there for my own code: glGetFloat(GL_MODELVIEW_MATRIX, modelBuffer); glGetFloat(GL_PROJECTION_MATRIX, projBuffer); glGetInteger(GL_VIEWPORT, viewBuffer); gluUnProject(mouseX, mouseY, 0.0f, modelBuffer, projBuffer, viewBuffer, startBuffer); gluUnProject

问题 I'm trying to implement a 'raypicker' for selecting objects within my project. I do not fully understand how to implement this, but I understand conceptually how it should work. I've been trying to learn how to do this, but most tutorials I find go way over my head. My current code is based on one of the recent tutorials I found, here. After several hours of revisions, I believe the problem I'm having with my raypicker is actually the creation of the ray in the first place. If I substitute

问题 I'm doing 3d visualization in python using pyglet, and need to retrieve the modelview and projection matrices to do some picking. I define my window using: from pyglet.gl import * from pyglet.window import * win = Window(fullscreen=True, visible=True, vsync=True) I then define all of my window events: @win.event def on_draw(): # All of the drawing happens here @win.event def on_mouse_release(x, y, button, modifiers): if button == mouse.LEFT: # This is where I'm having problems a = GLfloat()